Time between events template

Configuration
1

I’m trying to create a template that returns the number of seconds between one entity state change and another entity state change, to use in a sensors.

I have this:

{{ ((as_timestamp(states.binary_sensor.test_switch_1.last_changed) - (as_timestamp(states.input_boolean.previous_drum_wash.last_changed))/3600) | round(2))  }}

However, it seems to just be returning seconds since 1970, rather than the difference between the two events.

What do I need to change?

2

It looks like you are dividing just the last timestamp by 3600 instead of the resultant subtraction value which I assume is what you wanted

Check your parenthesis.

3

Thank you.

I’ve finally settled on this:

{{ (((as_timestamp(states.binary_sensor.test_switch_1.last_changed))) - (as_timestamp(states.input_boolean.previous_drum_wash.last_changed))) | round(0) }}

This returns the number of seconds between events.

Next step is the triggered template sensor, though I can’t get it to pass the config check.

- platform: template
    - trigger:
        - platform: state
          entity_id: binary_sensor.test_switch_1
          from: 'off'
          to: 'on'
      sensor:
        - name: time_between_washes
          state:  "{{ (((as_timestamp(states.binary_sensor.test_switch_1.last_changed))) - (as_timestamp(states.input_boolean.previous_drum_wash.last_changed))) | round(0) }}"
4

that’s because you are mixing “modern” & “legacy” template sensors.

“template” is it’s own integration separate from “sensor”.

the “sensor” integration has a platform “template”.

the “template” integration doesn’t.

try this:

template:
  - trigger:
      - platform: state
        entity_id: binary_sensor.test_switch_1
        from: 'off'
        to: 'on'
    sensor:
      - name: time_between_washes
        state:  "{{ (((as_timestamp(states.binary_sensor.test_switch_1.last_changed))) - (as_timestamp(states.input_boolean.previous_drum_wash.last_changed))) | round(0) }}"

see here:

5

Thanks again.

It’s working now.

Putting it ‘template’ instead of ‘sensor’ also makes a difference, it seems. :man_facepalming:

6

For future reference, last_changed contains a datetime object so you can perform subtraction directly. The result is a timedelta object so we can use its total_seconds() method to get what we want. The resulting template is more concise and has no nested parentheses.

        state: "{{ (states.binary_sensor.test_switch_1.last_changed - states.input_boolean.previous_drum_wash.last_changed).total_seconds() | round(0) }}"
7

That is excellent, thank you.

Is that available for total minutes too? Where in the docs would I find that?

There’s so much to templating that I don’t yet know.

8

It’s python.

Python timedelta.

total_seconds() is the timedelta object’s only method.

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